1. Field of the Invention
This invention relates to an image forming apparatus furnished with a finisher which is mounted in a copying machine or a printer and adapted to serve the purpose of bundling and stapling a plurality of copied or printed sheets, automatically encasing the stapled bundle of sheets with a cover specially designed for enclosure, and binding the cover.
2. Description of the Related Art
In recent years, some of such image forming apparatuses as copying machines and printers are furnished with an aftertreating device serving the purpose of automatically collecting sheets discharged from the apparatus, binding a bundle of these sheets with staples, encasing the stapled bundle with a cover specially designed for enclosure, and automatically binding the cover.
The cover specially designed to be used by the finisher of this description has fusible mucilage applied to such parts thereof as form an inside and a back. The finisher binds the plurality of sheets by encasing the sheets with the special cover and applying heat to the part of the cover forming the back thereby joining the sheets with the mucilage.
The bound documents are known in two types as sorted by the manner of binding, namely the documents of the right binding which binds a given document by applying mucilage to the right side of the document as illustrated in FIG. 29A and the documents of the left binding which binds a given document by applying mucilage to the left side of the document as illustrated in FIG. 29B. More often than not in the case of the documents written in the Japanese language, the documents having characters arranged vertically are in the right binding and the documents having characters arranged laterally are in the left binding.
Incidentally, the finisher which is mounted in the copying machine or the printer, on receiving sheets delivered from the copying machine or the printer, inserts the sheets in the same direction as used in the conveyance thereto into the special cover and binds them with the mucilage applied to the part of the back. As a result, it has the problem of betraying the inability to govern arbitrarily the distinction between the right binding and the left binding. Of course, it is not inconceivable that by incorporating a complicated switchback mechanism or a sheet inverting path in the sheet conveying path, the finisher is enabled to change mechanically the direction of sheet, depending on the selection between the right binding and the left binding, insert the sheets delivered in the selected direction into the special cover, and bind the cover. This measure, however, entails the problem of enlarging the apparatus and increasing the cost thereof.
Among the finishers of this class are included those which are provided with a sheet folding device capable of folding a discharged image-bearing sheet doubly in the central part thereof. The finisher which is provided with such a sheet folding device is enabled to fold a sheet doubly in the central part thereof and perform a stapling treatment on the edge part of the folded sheet to effect covered binding.
When a plurality of sheets are subjected to the covered binding, they may be bound on the right side (right binding) as illustrated in FIG. 30A or on the left side (left binding) as illustrated in FIG. 30B, when viewed from the front side of sheet. Also in the case of this covered binding, more often than not the documents having characters longitudinally arranged are bound on the right side and the documents having characters laterally arranged are bound on the left side.
In the case of the covered binding, however, while the sheets in a doubly folded state produce covered binding when they are found in the edge part, they produce no covered binding as illustrated in FIG. 31 when they are found on the opposite side, namely on the side forming a crease of fold. The right binding or the left binding cannot be arbitrarily selected simply by changing the sides to be bound.
A method for very simply solving this problem attendant on the covered binding as described above, for example, resides in providing a copying machine capable of copying original documents set therein sequentially from the first page onward with a finisher capable of giving each of the sheets the covered binding in the left binding. The copying machine, when operated to copy the original documents set therein sequentially from the last page backward, produces documents of the covered binding in the right binding. In this case, however, since the staples plunge into the bundle of sheets from the last page side as illustrated in FIG. 32, they give rise to the problem that the folded shanks of these staples finally rest on the front side of the first page and impair the appearance of the finished document. Further, the person engaging in the manual operation of the copying machine is compelled to do the work of rearranging all the original documents for printing. Thus, the automation of the covered binding possibly entails the problem of rather lowering the operational efficiency.